Two Categories of Organisms: Poikilotherms and Homeotherms

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INTRODUCTION Every living organism has a metabolism. Metabolism is the sum of the chemical reactions in one’s body, including both anabolic and catabolic processes (Pfleugal, 2014). These processes require energy that is obtained through the organism’s respiration. Because an organism’s respiration is linked to its energy consumption, researchers can observe changes in the metabolism of organisms by looking at their respiration rates. It is possible to measure respiration by looking at either the change in oxygen or carbon dioxide concentration in a closed environment. There are two categories of organisms: poikilotherms and homeotherms. Poikilotherms’ internal temperature varies constantly because they are reliant on the external environment, while homeotherms’ internal temperature is maintained relatively constant regardless of the external environment (Pfleugal, 2014). Because fish are poikilotherms, it is easy for researchers to observe changes in their metabolism due to changes in the external environment. One aspect in the external environment of fish that can be manipulated is the amount of caffeine in the water. This experiment will examine changes in oxygen concentration inside a chamber as a method of comparing goldfishes’ respiration and metabolic rates in two different fish water environments: regular (control) and caffeinated. Because caffeine stimulates the respiratory center resulting in an increase in the oxygen consumption, it is predicted that goldfish will have a higher oxygen consumption and metabolic rate when exposed to caffeine (Brinley, 2014). Thus, our hypothesis states there will be a statistically significant change in oxygen consumption between the two environments, and our null hypothesis states tha... ... middle of paper ... ...st four different people handled fish that were used to collect data. Each person handled the fish a little bit differently, which could cause variations of anxiety and fear in the fish. A lab worker, like myself, who has worked with fish for almost ten years, would likely cause less anxiety during transfer, when compared to someone who has never used a fish net before. Fish that were handled roughly could have quickened their heart rate and metabolism out of fear and anxiety, and thus would have consumed a disproportionately large amount of oxygen, which could skew results. To eliminate this potential source of error, we’d need to have a single person do the fish handling for all four groups. Overall, the data suggests that there is no significant difference between the metabolic rates of fish in regular fish water, when compared to fish exposed to caffeine water.

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